Health effects of carbon disulfide
Contents
Introduction
Pure carbon disulfide is a colorless liquid with a pleasant odor that smells sweet. The impure carbon disulfide that is usually used in most industrial processes, however, is a yellowish liquid with an unpleasant odor like that of rotting radishes. Carbon disulfide evaporates at room temperature, and the vapor is more than twice as heavy as air. Carbon disulfide easily explodes in air and also catches fire very easily. In nature, small amounts of carbon disulfide are found in gases released to the earth's surface, for example, in volcanic eruptions or over marshes. Microorganisms in the soil can also produce gas containing carbon disulfide. Commercial carbon disulfide is made by combining carbon and sulfur at very high temperatures. Several industries use carbon disulfide as a raw material to make such things as rayon, cellophane, and carbon tetrachloride. Currently, the largest user of this chemical is the viscose rayon industry. Carbon disulfide is also used to dissolve rubber to produce tires and as a raw material to make some pesticides. (Health effects of carbon disulfide)
Pathways for carbon disulfide in the environment
Carbon disulfide evaporates rapidly when released to the environment. The amount of carbon disulfide released into the air through natural processes is difficult to judge because it is in such small amounts in nature. This also makes it hard to monitor carbon disulfide and to explain how it behaves when it comes into contact with other compounds. Most carbon disulfide in the air and in surface water is from manufacturing and processing activities. However, it is found naturally in coastal and ocean waters. Carbon disulfide has also been found in the groundwater and soil at some EPA research sites around the country, but the number of research sites that have carbon disulfide is small.
Once released to the environment, carbon disulfide moves quickly to the air. Once in the air, carbon disulfide stays close to the ground because it is heavier than the surrounding air. It is estimated that carbon disulfide will break down into simpler components after approximately 12 days. Carbon disulfide moves through soils fairly quickly. Carbon disulfide accidentally released to soils normally evaporates rapidly. However, since carbon disulfide does not bind tightly to soils, the amount that does not evaporate can easily move down through the soil into groundwater. Since it is very mobile, it is not likely to stay in the soil long enough to be broken down. It does not remain very long in water either because it evaporates within minutes. However, if dissolved in water, it is relatively stable and is not easily broken down. It is estimated that carbon disulfide is not taken up in significant amounts by the organisms living in water.
Exposure to carbon disulfide
Carbon disulfide evaporates rapidly when released to the environment. The amount of carbon disulfide released into the air through natural processes is difficult to judge because it is in such small amounts in nature. This also makes it hard to monitor carbon disulfide and to explain how it behaves when it comes into contact with other compounds. Most carbon disulfide in the air and in surface water is from manufacturing and processing activities. However, it is found naturally in coastal and ocean waters. Carbon disulfide has also been found in the groundwater and soil at some EPA research sites around the country, but the number of research sites that have carbon disulfide is small.
Once released to the environment, carbon disulfide moves quickly to the air. Once in the air, carbon disulfide stays close to the ground because it is heavier than the surrounding air. It is estimated that carbon disulfide will break down into simpler components after approximately 12 days. Carbon disulfide moves through soils fairly quickly. Carbon disulfide accidentally released to soils normally evaporates rapidly. However, since carbon disulfide does not bind tightly to soils, the amount that does not evaporate can easily move down through the soil into groundwater. Since it is very mobile, it is not likely to stay in the soil long enough to be broken down. It does not remain very long in water either because it evaporates within minutes. However, if dissolved in water, it is relatively stable and is not easily broken down. It is estimated that carbon disulfide is not taken up in significant amounts by the organisms living in water.
Pathways for carbon disulfide in the body
Most people are exposed to carbon disulfide by breathing air that contains it. Carbon disulfide easily and rapidly enters your bloodstream through the lungs. Carbon disulfide can also enter your body through your skin, or by eating or drinking foods that are contaminated with the chemical. About 10-30% of carbon disulfide that the body absorbs leaves through the lungs; less than 1% leaves in the urine. The rest of the absorbed carbon disulfide (70-90%) is changed in the body and leaves the body in the urine in the form of other chemicals. Small amounts of carbon disulfide also leave the body in sweat and saliva.
Health effects of carbon disulfide
At very high levels (10,000 parts of carbon disulfide per million parts [ppm] of air), carbon disulfide may be life threatening because of its effects on the nervous system. Studies in animals show that high levels of carbon disulfide can damage the heart. People who breathed carbon disulfide near an accident involving a railroad car showed changes in breathing and some chest pains. Among workers who breathed about 8 ppm, some developed very slight changes in their nerves. Some workers who breathed more than 20 ppm during working hours for at least 6 months had headaches, tiredness, and trouble sleeping. However, the workers may have been exposed to other chemicals besides carbon disulfide. The current standard for exposure in the workplace is 20 ppm over an 8-hour day and a 5-day work week.
You should know that one way to learn whether a chemical will harm people is to determine how the body absorbs, uses, and releases the chemical. For some chemicals, animal testing may be necessary. Animal testing may also help identify such health effects as cancer or birth defects. Without laboratory animals, scientists would lose a basic method for getting information needed to make wise decisions that protect public health. Scientists have the responsibility to treat research animals with care and compassion. Scientists must comply with strict animal care guidelines because laws today protect the welfare of research animals.
Additionally, there are vigorous national and international efforts to develop alternatives to animal testing. The efforts focus on both in vitro and in silico approaches and methods. For example, the National Toxicology Program (NTP) at the National Institute of Environmental Health Sciences (NIEHS) created the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) in 1998. The role of NICEATM is to serve the needs of high quality, credible science by facilitating development and validation—and regulatory and public acceptance—of innovative, revised test methods that reduce, refine, and replace the use of animals in testing while strengthening protection of human health, animal health and welfare, and the environment. In Europe, similar efforts at developing alternatives to animal based testing are taking place under the aegis of the European Centre for the Validation of Alternative Methods (ECVAM).
Studies in animals indicate that carbon disulfide can affect the normal functions of the brain, liver, and heart. However, the amount of carbon disulfide in the air to which animals in these studies were exposed was much higher than the amounts in the air that the general public usually breathes. The brains, livers, and hearts of the animals were affected only after breathing air that contained carbon disulfide for days, months, or years. After pregnant rats breathed 225 ppm carbon disulfide in the air, some of the newborn rats died or had birth defects.
There is no information on health effects in people who eat food or drink water contaminated with carbon disulfide. Animals fed food that contained carbon disulfide developed liver and heart disease, and some showed abnormal behavior. These amounts, however, were very much higher than those that occur in drinking water supplies. When pregnant animals received large doses of carbon disulfide in their diet, some of the newborns died or had birth defects.
Skin contact with spilt carbon disulfide can lead to burns at the contact site. In studies that examined the harmful effects of skin contact with carbon disulfide, workers in a rayon plant who handled fibers made with carbon disulfide for more than 14 days developed blisters on their fingers. Rabbits developed blisters and ulcers on the treated areas of their ears.
Medical tests for exposure to carbon disulfide
Carbon disulfide itself can be measured in breath, urine, and blood. It breaks down in the body into other chemical substances called metabolites. These substances can be found and measured in the urine. After carbon disulfide enters your body, these substances reach higher levels than normally found. One chemical test using urine can be done to tell whether the levels of these breakdown substances from carbon disulfide are higher than normal. This test requires special equipment and is not routinely available in a doctor's office. The test is not specific for carbon disulfide exposure because other chemicals can also produce these metabolites. Therefore, it cannot be used to find out exactly how much carbon disulfide you were exposed to or to predict whether you'll be harmed. Also, the test can only be used if you have breathed in at least 16 ppm; this test can be used for determining longer term exposure to carbon disulfide. A second test based on a specific metabolite is more sensitive and specific. It also requires special equipment and cannot tell you exactly how much carbon disulfide you were exposed to or predict whether you'll be harmed. Carbon disulfide leaves the body quickly in the breath and in the urine.
Further Reading
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